1. Field of the Invention
The present invention relates to heavy duty liquid detergent compositions which contain a novel encapsulation system. In particular, the invention relates to compositions containing capsules which capsules comprise
(1) non-proteolytic enzymes (e.g. lipase) subject to degradation by other enzymes (e.g. protease) in the composition; and PA0 2) a composite polymer which comprises hydrophobic core particles to which are chemically and/or physically attached hydrophilic polymer or polymers. The non-proteolytic enzymes are entrapped within the composite polymer.
2. Prior Art
It is well known in the art that heavy duty liquid detergents provide a hostile environment for non-proteolytic enzymes. The enzymes may be denaturated, for example, by surfactants in the composition or subject to proteolytic digestion by protease enzymes in the composition. A number of methods are known in the art for protecting and stabilizing enzymes or other components in such heavy duty liquids from denaturation or from proteolytic digestion. Typically, stability from proteolytic digestion is accomplished by reducing proteolytic activity (i.e., inhibiting the enzyme) This reduces proteolysis and results in better stability of the non-proteolytic enzyme.
A number of patents teach the use of a combination of a polyol and a boron compound as an enzyme stabilization system. Thus, Canadian Patent No. 1,092,036 (Hora et al), for example, discloses enzymatic liquid detergents containing 4-25% polyol and boric acid (or boron equivalent) in a weight ratio of polyol to boric acid less than 1; and U.S. Pat. No. 4,404,115 to Tai teaches the combination of alkalimetal sulphite and/or polyol as an enzyme stabilizing system.
U.S. Pat. No. 4,518,694 to Shaer teaches the use of carboxylic acids as enzyme stabilizers and U.S. Pat. No. 5,073,292 teach the stabilization of proteins using specified proteins (i.e., proteins containing quaternary nitrogen substituents).
U.S. Pat. No. 5,080,163 to Aronson et al. teaches a composition for stabilizing proteolytic and non-proteolytic enzymes using a stabilizing system comprising a polyol and a boron compound wherein the compounds react with one another and the polyol has defined first and second binding constants.
None of these references teaches or suggests the protease containing compositions comprising the non-proteolytic enzyme capsules of the invention.
Yet another way of stabilizing an enzyme is by physically separating the enzyme from the medium causing degradation. U.S. Pat. No. 4,906,396 to Falholt et al., for example, teaches coating the enzyme in a hydrophobic substance such as silicone oil and which substance is sufficiently fluid or friable to be disrupted under normal conditions of use.
Many references also teach the encapsulation of sensitive components which are released at a desirable time subsequent to encapsulation. None of these references, however, teach the capsules of the invention.
European Patent Application No. 266,796 (assigned to Showa Denko), for example, teaches water-soluble microcapsules comprising an enzyme, preferably dissolved or dispersed in a water containing hydroxy compound and coated with water-soluble polyvinyl alcohol (PVA) or partially hydrolyzed polyvinyl alcohol as the coating material. There is no teaching or suggestion of a composite polymer comprising network formed by hydrophilic polymer or polymers chemically and/or physically attaching to the hydrophobic particles and in which system or network non proteolytic enzymes is entrapped. By being entrapped, the non-proteolytic enzyme is protected from attack by the protease present in the composition. In addition, the PVA used in the Showa Denko reference, in contrast to the PVA which could be used as the hydrophilic polymer of the subject invention, has an average degree of polymerization in the range of 200-3000 and a percent hydrolysis not less than 90%, preferably not less than 95%. It is said that if the percent hydrolysis of PVA is lower than 90%, the microcapsule is not stable and will dissolve during storage in a water-containing liquid detergent. This is probably not surprising in that there is nothing to stabilize the capsule other than a cross linking agent, i.e., there is no teaching or suggestion of hydrophobic "core" particles comprising an ethylenically unsaturated group to which the hydrophilic polymers can affix, chemically or physically, to form an entrapping network.
That is, the encapsulating polymer of this reference comprises only the use of a water soluble polymer (i.e., PVA) rather than an entrapping polymer which is a composite emulsion copolymer comprising both water-soluble (i.e., hydrophilic attaching polymer) and water insoluble (i.e., hydrophobic particles to which hydrophilic polymers attach) components or domains. The use of a totally water soluble polymer does not provide optimal resistance to water. Such polymers are also more difficult to process than the composite polymers of this invention. Finally, at the levels of hydrolysis for PVA taught in this reference (i.e. greater than 90%, preferably greater than 95%), it is difficult to dissolve the capsule or polymer at ambient temperatures and the protected component is only partly released upon dilution. Moreover, the reference does not allow the option of using less hydrolyzed PVA because, although the less hydrolyzed PVA will dissolve more readily when diluted, such a PVA is too water sensitive and would fail to protect the component during storage.
U.S. Pat. No. 4,906,396 to Falholt et al., teaches an enzyme dispersed in a hydrophobic substance. Again, there is no teaching or suggestion of a polymer which is a composite emulsion copolymer comprising both water soluble and water insoluble components.
EP 1,390,503 (assigned to Unilever) teaches a polymer which dissolves when the ionic strength of the liquid decreases upon dilution. Further, there is no teaching of a polymer system comprising a composite emulsion polymer which in turn comprises a hydrophilic portion (i.e., hydrophilic polymer or polymers) chemically and/or physically attached to a hydrophobic core portion (i.e., hydrophobic particles) to form an entrapping emulsion polymer in which the enzyme component is trapped.
Takizawa et al. (U.S. Pat. Nos. 4,777,089 & 4,908,233) teach the use of a microcapsule which comprises a "core" material (i.e., the protected material is the core) coated with a single water soluble polymer (which polymer undergoes phase separation by the action of an electrolyte in the compositions). Again, there is no teaching or suggestion of a composite emulsion polymer comprising a hydrophilic portion chemically or physically attached to hydrophobic core particles and used to entrap non-proteolytic enzymes. Such a composite polymer having both a hydrophilic and hydrophobic portion offers significant advantages over the solely water-soluble encapsulating polymers of the reference in that it entraps the enzyme and slows migration of harsh components from outside the capsule to the enzyme as well as migration of the enzyme to water and other components outside the capsule.
U.S. Pat. No. 4,842,761 to Rutherford teaches compositions and methods for controlled release of fragrance-bearing substances (perfumes) wherein the compositions comprise a water-soluble and a water-insoluble (both normally solid) polymer and a perfume composition, a portion of the perfume composition being incorporated in the water-soluble polymer and a portion incorporated in the water-insoluble polymer. The two polymers are physically associated with each other in such a manner that one is in the form of discrete entities in a matrix of the other. The particles of this reference have a particle size of between 100-3000 microns in contrast to the capsules of the invention which have a particle size of under 100 microns. In addition, the capsules are formed by intermixing water soluble and water insoluble polymer under high shear resulting in a different capsule system than the emulsion polymer capsule of the subject invention.
Applicants co-pending U.S. Ser. No. 07/766,477 teaches a water soluble polymer used to encapsulate particles made of an emulsifiable mixture of a fragrance and a wax. The waxes used are hydrocarbons such as paraffin wax and microcrystalline wax. These waxes differ from the core hydrophobic particles of the invention. Moreover, the core is not simply a wax material enveloping the perfume but an intimate mixture of the wax and perfume which differs completely from the core particles of the subject invention which may stand alone. In fact, the enzymes of the subject invention are not inside the hydrophobic core particles at all. Finally, the encapsulated material of the reference is released by heat trigger whereas the release of material of the invention is dilution triggered.
U.S. Pat. No. 4,115,474 to Vasilliades discloses a hydroxy containing polymer shell grafted onto a water soluble core. The hydroxy shell is cross-linked with a formaldehyde condensation product and will therefore not release upon dilution by water. Moreover, the reference does not refer to entrapped sensitive materials which can be released. Indeed, the capsule is intended to be a load bearing capsule which is not ever subject to pressure release.
None of these patents teach capsules comprising the specific composite emulsion polymers of the invention in any composition, let alone in heavy duty liquid compositions.
Thus, there is a need in the art for protease containing heavy duty liquid compositions containing capsules comprising novel composite polymers which can stabilize non-proteolytic enzymes, and yet readily break down to release the enzymes in use (e.g., in diluted aqueous medium, especially at ambient temperatures).
Accordingly, it is an object of this invention to provide protease containing heavy duty liquid compositions that incorporate capsules comprising a novel composite polymer that can stabilize and isolate non-proteolytic enzymes while simultaneously being able to deliver the enzymes in a controlled and reproducible manner when the composition is diluted with water during use.